US2330518A

US2330518A - Hydraulic jack

Info

Publication number: US2330518A
Application number: US416881A
Authority: US
Inventors: Rothery James Stewart
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-06-24
Filing date: 1941-10-28
Publication date: 1943-09-28
Anticipated expiration: 1960-09-28

Description

Sept. 28, 1943. J. s. RQTHERY 2,330,518

HYDRAULIC JACKS FiledOpt. 28, 1941 2 Sheets-Sheet l Jude/1Z7;

Ei/LEJ 5"- Sept. 28, 1943. J. s. ROTHERY 2,330,513

HYDRAULIC JAGKS I Filed 001:. 28, 1941 2 Sheets-Sheet 2 ing for use with hydraulic rams. V n V I According to one feature of the 1nvention=.-the

ranged atfdifiering heightsin the slee Patented Sept. 28, 1943 I nxnmmme men Y n v James Stewart Bowery, inqrqgnnglarrd 5' I i Application (jctober 2s, mus el Ni}. MEBQL;

. InGrea't Britain June 24,;1941'1 awnin (01. mean; p e I This invention relates to means'f or locking: the extended ram of anhydraulic jack. against unintentional collapse which might occur owing to small leakage or other reason and to apackram of: an hydraulic jack is provided with a number of. superposedvholesthrough lit,,l'preferably in vertical alignment, andiarioundlthelram on the. head of the jack frame orl structure or "of. the cylinder is a rotatable' sleevel'iaving it a plurality ofholes preferably impairs; the two holes breach pair being diametrically opposite e'achother andthe pairs oi holesfar- M 0 that" to whatever'height the ram may beli edtlie' sleeve can'be rotated so-as-to'bring ohe "of the pairs of holes iii-it opposite"ornearlyopposit to, i. e., substantially into coincidence with, a hole intl'ie ram aiter' which apin, say on achain, is inserted from" one side or the sleeve througlr the hole therein and through thehole in the ram and the corresponding hole on" the. other side of the sleeve.

It will be: seen from theabovethat whenthe: ram" has' beenz'extended'to the desiredheightthe sleeveis rotated uhtil thepin can-he pushed" throughthepair of holes coincidin'gwith ahele" in the ra In-which-is then locked and any drep will not exceed,/at'the most; the-vertical-distance; between the centres of one pair: of holes in the sleeve. A secondary sleeve tor-other device) screwed inside or outside the main sleeve could.

be arranged-totake up this "p1ayif desired but such fine adjustment is not usually required.

Sufficient adjustment. may alsobe obtainedbyv having thetholes elongated, the line of lelong'a tion rising slightly so rthatfa fractional turn "of. the sleeve gives the required ad ustment;,

The diametral. holes in. the. .ramj prleclude the. satisfacto provision of a. packingjgl'aridf'at the top, of the cylinderfand in' orider to prevent" the escape of working liquidthat? leaks past 1th? cup leather or like normal ram packii'igfafsaietyf seal has been devised and applied} to -the ram above the saidcup leather or the like inacjcord anee'fwith'a" furtheniea'ture of the-"inv'e rltion=;a In order to" prevent the jack being raised ihei yond a predetermined heightthe cylinder has-a vent-or an exhaust valve which, when comm-unieatingi withthefpres'sure chamber of the jackowing to the jackbeingraised to thesaid'hei'g ht; allows the working liquidto-return tothe rese1 vo'i-r. Such-en arrangement is diS'elbseddintlie specification of niy- U. S. Patent N01 to eachother; and around the ramand ,resting Accordingto; a still furtherv feature oft-the invention, however, the; saidyalve is of non return type whereby liquid is prevented: from; returning to'the cylinder when-thejack is lowered and-escaping by Way of the unpacked top of:- the cylinder; r

The safety seal and the; vent with'z-the non return valve may be used with other: types of hydraulic jacks, for; example, jacks having ex-- ternally screw-threaded rams on" which isa nut which can be set longitudinally of the ram'to, sustainit bythrusting against the top 0f the jack. 1

Therinvention will now be described with referer rce to the accompanying drawings wherein: Fig; 1 .isa perspective view 1 of the jack, the

ram being lowered:

fig; 2C isaside el'evation; partly. in section,

showing tl'ie'top" of: the jack cylinder, the .rotat-v ahlesleeve and'theilower part of the ram with a saiety seal. v I y i Fig; 2 'ls a .det'ailoi 'a-modifiedformoi safety seal.

Fig.1 3 is a purposes: and

Fig. 4 is :a fragmentary view of a jack incorporating a; sleeve with-elongated holes.-

The-jackshownin- Fig. 1 comprises-thetubular tripod I from the peak of which-the ram cylinder 2 depends, the legs beingflbraced toe and into the 'reservoir-toallow the ram to sink The? jackias described so far is substantially as described in my;said- U; S. patent specification rAceordingqto one feature of the present'invention theram :1 Fig; 2; is provided with a number of pairsofs vertically superposed holes 8,- the;

holes; of each pair being diametrically 1 opposite on, a'iguide collar .9 1f01 the ram. is: a sustaining element comprising a 'rotatable sleeve :l-il' in which are a number of pairsof holes I l. The centresiofg the-holes ll lieon a double helix-so that eachholehasanother diametrically opp'o site to it andlea-chpair of holes isat-a difierent' "$214,440; heighthfromthei others. The guide collarfiyis;

fragmentary viewxof a jack incorporatihgta secondary. sleeve for' fine adjustmentfianged at I2 and the flange rests on the top of the cylinder 2.

In use, the jack is raised, 1. e., the ram is lifted, to bring the crutch I3 (Fig. 1) into engagement with the article to be sustained, the sleeve I is turned to bring two of its holes into register with a pair of holes 8 and a pin I4 is thrust into the four aligned holes and locks the ramin the raised position, the ram thrusting downwardly onthe pin if able to overcome the pressure of the work; ing fluid, the pin thrusting on the collar and the collar thrusting on the cylinder through the flange I2 of the guide collar. I The collar 9 is provided in lieu of a packing gland. To overcome the disadvantage arising,

from the absence of a gland at the top of the cylinder the ram is provided with a s'a'fetyseal' I5. This seal is located at the reduced'bottomof the ram above the usual cup leather I6, said cup leather being secured to the ram by means of a washer II and a bolt I8 whichenters a plug I9 forcedinto the bottom of the ram. V a

The seal comprises a packing ring 28 in the lower annular surface of which is a V-groove; and an expander ring ll of triangularcross section but less in height as regards the Vsection than the groove is deep lies in the groove so 'as to expand the lips of the'groovefirst. The expander rests on the-upper portion of that part of the surface of a flange 22 on th plug I9 which projects beyond the sides of" the ram whilst a movable collar 23 with an externalflange 24 at its bottom end rests on the top of the ring 2B.. Above the collar 23 and bearing against the shoulder 25 on the ram formed by reducing the latter is a collar 26 like 23 but inverted, the flange 21 of said collar 26 thus being at the-top; and between the

flanges

21 and 24 is a spring 28 which thrusts the collar 23 into contact with. the ring 1M3. The ring in turn thrusts against the expander and as the expander is held against downwardmovement relatively to the ring by the flange 22 the lips of the groove in the ring are splayed and make closecontact with the cylinder and the outer surface of the ram, respectively. Liquid which leaks past the leather I6 is able to raise the seal I5 until the collar 23butts against the collar 26. Thereafter :the liquid is trapped until pressure on the leather'is'released whereupon the spring is able to expand to the position shown and the seal I5 drives the liquid back into the cylinder past the said leather. Either collar (23, 26) may be considerably shorter than shown and the other as shown-or longer," Spring-means maybe employed to expand the cupleather in order'to ensure that the seal I5 does not the work of the said leather. I

A seal comprising a groove and expander hav-' ing sections differing from a vm'aybe' used. Fig. 2 shows one alternative form. In this case the do all underside of the ring ZD'has'a groove of half round sect-ion and the expander ring 2| is of corresponding shape, the radius of curvature, how-' ever," ofthetop ofthe expanderbeinggreater than that of the groove to ensure outward move ment of the groove lips by the expander.

If the jack be laid onits side orinverted the seal I5 will prevent the flow of liquid to that end of the cylinder at which thecollar 9 is located.

When the bottom of the ram nearly reaches the top of the cylinder the leather I6 passes a hole 28 in the cylinder and further upward movement of the ram is prevented asthe hole allows the working liquid to escape from the cylinder, The liquid is conducted to the hollow of one of the members 3 by means of a valve and a pipe 30; and in accordance with the invention the valve 29 is of non-return type so that the liquid cannot flow back into the cylinder and escape past the collar 9 ifthe jack is laid on its side or is inverted.

In Fig. 3 an externally screw-threaded, hollow bush 3| is interposed between the flange I2 and the. collar III, the lower part of the bore of the said collar being screw-threaded for engagement with the bush. Thus the collar II] can be raised or lowered to permit of adjustments which are fractional parts of the vertical distance between any two successive holes I I.

In Fig. 4 the collar III has holes 32 arranged similarly to the holes II, Figs. 1, 2 and 3, but of elongated form, the major axes of the holes lying on the helices on which the centres of the holes lie. Thus, the collar permits of finer setting of the jack than is possible with the collar shown in Figs. 1 and 2 as parts of a pair of elongated I holes can be exactly registered with two holes as,8 by turning the collar through an angle less than that lying between the centres of two successive holes. a

What I claim is:

1. On an hydraulic jack comprising a cylinder, 2. ram operative in the cylinder, a ram sustaining element encircling the ram and supported solely by the cylinder and freely rotatable with respect to the ram and cylinder, said element having holes along its length at different distances from its ends and said ram having holes along its length, and a free pin to be passed through transversely registering holes in the sustaining element and in the ram whereby the ram is :held against sinking with relation to the cylinder.

2-. On an hydraulic jack comprising a ram in a cylinder, a, freely-rotatable sleeve mounted on said jack in'surrounding relation to said rain at the top of the cylinder, said .sleeve having holes in diametrically-opposed pairs along, its length, each pair of holes being at relatively difierent distances from its ends and said ram having holesalong its length, and a free pin, said pin being adapted to enter a holein the sleeve and a hole in the ram whereby the ram is held against sinking with relation to the jack cylinder.

3. On an hydraulic jack according to claim 2, said'sleev e having holes the centres of which lie on a helix. x

4. On an hydraulic jack according to claim 2, wherein the sleeve is vertically adjustable with respect to "the ram' and wherein the centers or the respective diametrically-opposed pairs of holes lie on helices and said ram having diametralholes.

5. On an hydraulic jack according to claim 2, said sleeve having elongated holes/the centres of whic'nlie on a.helix and the major axes of which rise slightly.

6. On an hydraulic jack according to claim 2, said sleeve having a screw-thread, a screwthreaded bush engaging with said screw-thread on said sleeve, said bush being rotatably mounted onthe jack. I

7. In anhydraulic jack according to claim 2, a guide collar arranged between the ram and cylinder and providing a bearing contact for the ram, said collar being mounted in the upper end of the cylinder, a flange on said guide collar bearing against the top ofthe cylinder, and said fluid from such reservoir under pressure for operating the ram.

9. A construction as defined in claim 2, wherein means are provided for preventing any leakageof operating fluid from reaching the sleeve.

10. A construction as defined in claim 2, wherein spring operated means are provided to prevent leakage of operating fluid from reaching the sleeve, and wherein such spring operated means automatically returns such leakage for power service on the ram.

JAMES STEWART ROTI-IERY.